Carrying Capacity

Another example of complex interactions that can take place within an ecosystem occurs when one species exceeds the carrying capacity of their ecosystem. Carrying capacity is the number of individuals of one species that an ecosystem can support over time, without changing the ecosystem. If one species exceeds the carrying capacity of its ecosystem, harmful changes can occur. For example, if too many cattle are allowed to graze uncontrolled in a mountain pasture, it can affect the vegetation. Not only do cattle eat (and sometimes overeat) the grass and shrubs in their ecosystem, but their hooves pack down the soil. This prevents plants from growing because their roots cannot become established. Also, water and nutrients cannot penetrate into the soil if it is compacted. Without the roots of established vegetation, the soil is easily eroded and can lead to long term deterioration of the ecosystem.

Humans can also exceed the carrying capacity of their environment. Beginning in the 1800s, deforestation of the eastern United State's forest ecosystems began to become more widespread. Trees were cut down as a source of fuel, to construct towns, and create more agricultural land. Deforestation (without proper reforestation) results in a loss of biodiversity, damages habitats, increases soil erosion, reduces the amount of nutrients in the soil, and can lead to the extinction of species, Another way humans exceed their ecosystems' carrying capacity is through pollution. Industrial, agricultural, and urban pollution can damage Earth's water bodies and the atmosphere, and can have long-term consequences for nearby ecosystems.